Optical head structures including support substrates adjacent transparent substrates and related methods

ABSTRACT

An integrated optical head, such as, for a disk drive, preferably includes an optically transparent substrate. The substrate has a diffractive optical element formed on one face and a plurality of electrical contact pads exposed on the other face. A light source is positioned to emit light through the substrate, through the diffractive optical element, and toward data storage media. The light source includes a plurality of electrical contact pads corresponding to the plurality of electrical contact-pads exposed on the face of the substrate. An optical detector is positioned to detect light reflected from the data storage media, through the diffractive optical element, and through the substrate. The optical detector includes a plurality of exposed electrical contact pads corresponding to the plurality of electrical contact pads exposed on the face of the substrate. The substrate and the light source and optical detector are passively aligned using solder bumps between pairs of contact pads. A mechanical passive alignment arrangement is also disclosed.

Related Applications

This application is a continuation-in-part application claiming prioritybased on U.S. patent application Ser. No. 08/727,837, filed Sep. 27,1996, now U.S. Pat. No. 5,771,218, issued on Jun. 23, 1998, and entitled"Passively Aligned Integrated Optical Head Including Light Source,Detector, and Optical Element and Methods of Forming Same" thedisclosure of which is hereby incorporated herein in its entirety byreference.

FIELD OF THE INVENTION

The present invention relates to the field of optics and, moreparticularly, to an integrated optical head, such as for use in a diskdrive.

BACKGROUND OF THE INVENTION

Many typical computer systems include a disk drive cooperating withstorage media to permit storage and retrieval of data. A typical opticaldisk drive includes an optical head that conventionally uses a laser totransmit light to the optical disk. Light reflected from the surface ofthe disk is detected by an optical detector and processed to read datafrom the disk. An example of such an optical head is disclosed, forexample, in U.S. Pat. No. 5,204,516 titled "Planar Optical Scanning HeadHaving Deficiency-Correcting Grating" by Opheij. The size of the variousoptical head components, however, are often too large for many desiredapplications and many market demands. Also, as densities of integratedcircuits and system boards increase, the demand for smaller componentsincreases. Additionally, the production process for a conventionaloptical head requires that the laser be excited or turned-on (i.e.,"active alignment") for alignment of the laser, the detector, and theoptical elements. An example of active alignment processes isillustrated and described in an article published in Optical Engineering(June 1989) titled "Holographic Optical Head For Compact DiskApplications" by Lee.

Unfortunately, these active alignment requirements are complex, timeconsuming, and relatively expensive. Further, the level of sizereduction in the vertical direction of an optical head is limited. Inaddition, the relatively large size of the elements of an optical headwhich can be manipulated is determined by the need for active alignment.

SUMMARY OF THE INVENTION

With the foregoing background in mind, it is therefore an object of thepresent invention to provide an optical head, such as for a disk drive,and related methods which is more compact and less expensive tomanufacture.

This and other objects, advantages, and features of the presentinvention are provided by an integrated optical head that relies onpassive alignment of the various components. The integrated optical headpreferably includes an optically transparent, substrate having first andsecond faces. The transparent subtrate may include a diffractive opticalelement formed on the second face of the transparent subtrate. Anoptical light source, such as a laser and an optical detector can beprovided on a support substrate, such as a silicon substrate, andpassive alignment means can be positioned between the first surface ofthe transparent substrate and the support substrate for passivelyaligning the two substrates. The light source and the optical detectorcan thus be aligned with respect to the transparent substrate. Moreparticularly, the light source transmits light through the transparentsubstrate, through the diffractive optical element, and toward a target,such as optical storage media. The optical detector detects lightreflected from the storage media, through the diffractive opticalelement, and through the transparent substrate.

Accordingly, the laser and detector may also be aligned with the opticalelements on the second surface of the transparent subtrate.

An optical head according to the present invention may provide a sizereduction of more than three times compared to the prior art, in part,based upon photolithographically shaped and placed refractive opticalelements, as well as diffractive optical elements. Further, the laserand detector are preferably also accurately and passively aligned bymeans of photolithography. More particularly, in one embodiment, passivealignment is achieved by the wetted area and volume of solder inopposing alignment areas provided by contact pads.

In another embodiment, a second transparent substrate is aligned andjoined to the first transparent substrate.

The second transparent substrate may carry one or more optical elements.According to this aspect of the invention, alignment areas in the formof benches or other mechanical features may be formed in one surface andmating recesses, for example, may be formed in the other surface.Adhesive attachment areas, which may overlap the alignment areas, holdthe substrates together. Alignment may also be accomplished at the waferlevel by having the elements of each die accurately placed usingphotolithography to accurately align the two wafers. The assembled diescan then be diced without the individual alignment means or steps beingrequired for connecting the first and second transparent substrates.

Methods of forming an optical head are also provided according to thepresent invention. A method of forming an optical head preferablyincludes forming at least one optical element on a first face of atransparent substrate and positioning a laser adjacent the first face ofthe substrate so as to emit light through the substrate, through the atleast one optical element, and toward the data storage media. An opticaldetector preferably is positioned adjacent the first face of thetransparent substrate adjacent the laser to detect light reflected fromthe data storage media, through the substrate, and to the opticaldetector. The laser, the optical detector, and/or the at least oneoptical element on the substrate may passively aligned using either thecontact pads and solder bumps, or the mechanical alignment as discussedabove.

An integrated optical head and the related methods according to thepresent invention advantageously provide a significantly smaller opticalhead for fabrication without the need for exciting or turning on thelaser light source to actively align the components. The integratedoptical head according to the present invention overcomes thedisadvantages of the prior art so that the wavelength of the laser isleft as the predominant limiting factor in size reduction instead ofother considerations.

BRIEF DESCRIPTION OF THE DRAWINGS

Some of the objects and advantages of the present invention having beenstated, others will become apparent as the description proceeds whentaken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic view of an integrated optical head according tothe present invention;

FIG. 2 is a fragmentary side perspective view of an integrated opticalhead according to the present invention;

FIG. 3 is a side elevational view of an integrated optical headaccording to the present invention;

FIG. 4 is side elevational view of the integrated optical head as shownin FIG. 3 rotated ninety degrees.

FIG. 5 is a plan view of the component side of a first transparentsubstrate of an integrated optical head according to the presentinvention;

FIG. 6 is a plan view of a holographic optical element of a firsttransparent substrate of an integrated optical head according to thepresent invention;

FIG. 7 is a plan view of a refractive lens surface of a secondtransparent substrate of an integrated optical head according to thepresent invention;

FIG. 8 is a plan view of diffractive optical elements of an integratedoptical head according to the present invention;

FIG. 9 is an enlarged view of mask portions of FIG. 4 according to thepresent invention;

FIG. 10 is a perspective view showing an article including two wafersaccording to the present invention;

FIGS. 11A-11D are vertical fragmentary sectional views of examplealignment features according to the present invention; and

FIG. 12 is a vertical sectional view of a substrate showing a method ofcreating a hybrid microlens for an integrated optical head according tothe invention.

FIG. 13 is a cross sectional view of a first integrated optical headincluding a transparent substrate, and a light source and an opticaldetector on a support substrate adjacent the transparent substrateaccording to the present invention.

FIG. 14 is a cross sectional view of a second integrated optical headincluding a transparent substrate, and a light source and an opticaldetector on a support substrate adjacent the transparent substrateaccording to the present invention.

FIG. 15 is a cross sectional view of a third integrated optical headincluding a transparent substrate, and a light source and an opticaldetector on a support substrate adjacent the transparent substrateaccording to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theillustrated embodiments set forth herein. Rather, these illustratedembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the invention to thoseskilled in the art. Like numbers refer to like elements throughout, andprime and double prime notation are used to indicate similar elements inalternative embodiments.

FIG. 1 is an optical design schematic of an assembly according to theinvention for use in detecting an optical track on a storage media. Alight source 10 directs coherent light, with a dispersion angle offifteen degrees, upward through an object distance d1 through adiffractive element (DOE) not shown and to a refractive lens 12. The DOEdivides the light into a number of beams, only three of which are shownas a plurality of rays in FIG. 1. The beams are focused on surface 14located at image distance d2 from the lens 12. The spot size and spacingof the light on the image surface 14 determines the tracking accuracyand therefore the amount of information that can be stored on the media.The size to which the spot can be reduced is in the instant design,approximately 0.020 mm. In the design of FIG. 1, the refractive lens 12must have a significant curvature in order to focus the light to 0.020mm spots on the media. The spots of light are spaced approximately 0.100mm from each other on the media to limit crosstalk noise. As would bereadily understood by those skilled in the art the optical head can bepositioned by the illustrated positioning means 29.

If a design were attempted using a single lens as taught in the priorart, the lens curvature required to focus the laser light to 0.020 mmspots in this compact architecture would control the dimensions of thesingle lens. Thus the use of a single lens as taught in the prior artfor reducing the size of optical heads, is a limiting factor in sizereduction of the entire optical head assembly. This factor is one of thereasons that multiple lenses are employed in the instant inventioninstead of a single lens.

The distance d1 is used to advantage to provide an adequately wide beamat the DOE as shown later with respect to FIG. 7. The distance d2 ischosen to achieve adequate spot size modulation depth and depth of focusat the media surface.

The ratio of the distances d1/d2 determines the amount ofdemagnification of the image reflected from the media that occurs in alens. In a single lens design, this demagnification affects not onlyspot size but spot spacing. A demagnification of 1/4 gives a spot sizeof 0.005 mm which because of aberration is spread to an area 0.025 mm.If a single lens design had been used, the spacing of the spots wouldalso have been demagnified to 0.025 mm and significant crosstalk noisewould result. By using individual lenses, spaced approximately 0.200 mm,the detectors can be spaced at about 0.220 mm and thereby eliminatecrosstalk noise using the 0.025 mm light spots.

FIG. 2 is a side view of a magnetic floppy disk head 5 with an opticaltracking assembly according to a preferred embodiment of the invention.Head 5 is mounted, in arm 3 by known means not shown, for the extensionacross the various tracks of media 31. Head 5 is electrically connectedto read and write circuits and tracing control circuits by a flexibleprinted circuit 7. A recess 9 of approximately two millimeters by onepoint six millimeters and four and a half or five millimeters deep isprovided in head 5 in which the optical assembly comprising substrate 11is mounted and connected to flexible printed circuit 7. It will beappreciated that the same assembly techniques and methods of theinvention may be used to assemble optical disk read heads, as well asmagnetic disk heads with optical tracking.

Referring now to FIG. 3, a first transparent substrate 11 comprisingfused silica or other optical material has component mounting metalizedpads or contact pads placed on its bottom surface 13, such as usingsubstrate fiducial marks or indicia and accurately alignedphotolithographic masks and metal deposition steps known in the art ofmicroelectronic circuit manufacture. In this preferred embodiment,surface 13 of substrate 11 is approximately 1.6 mm by 2 mm and thesubstrate 11 is approximately 0.8 mm thick.

A laser chip 15 is mounted to the surface 13 by means of some of thementioned metalized pads. As shown in FIG. 4, laser 15 is an edgeemitting laser with the laser light directed upwards through means of aprecision mirror 33 as shown in FIG. 4. It will by understood that theedge emitting laser 15 can be replaced with a vertical cavity surfaceemitting laser and thereby obviate the need for the precision mirror inorder to direct the laser beam normal to the substrate surface.

An optical detector chip 17 is also mounted to the component surface ofsubstrate 11 by means of the metalized pads. A hologram surface 19 onthe opposite side of substrate 11 carries the diffractive opticalelements shown in detail in FIG. 7. The diffractive optical elementphase profiles are designed using the computer calculations andmanufactured using techniques taught by Swanson et al. in U.S. Pat. No.5,161,059, the entire disclosure of which is incorporated herein byreference.

The optical elements are created photolithographically using the samefiducial marks or indicia used to place the metalized pads. Alternatelysecond fiducial marks that have been aligned with the first marks may beused to align the masks that are also used to create the opticalelements. In this way when the light source, mirror and detector aremounted on their metalized pads, the optical paths among the devices andthrough the optical elements are in optical alignment as shown moreclearly in FIGS. 3 and 4. The precision mirror, if needed forredirecting light from an edge emitting laser, is considered to be adevice for the purposes of this description only because of the way itis mounted using metalized pads and solder as a silicon chip would bemounted. The hologram surface 19 also has the attachment areas 23 thatattach the first transparent substrate 11 with a second transparentsubstrate 21. These attachment areas and later described alignment areasare shown in detail in FIGS. 11 and 12.

The second substrate 21 carries the refractive optics in a surface 25that provides the second lens of lens pairs or doublets. Light fromlaser 15 is shaped-and split by a diffractive optical element inhologram surface 19 into five separate beams of light that are directedthrough substrate and travel approximately 2.4 mm to the media. Only thechief ray of each beam is shown in FIG. 3 for clarity of thedescription. One beam is used for intensity feedback to control theelectrical power to laser 15. The other four beams are used for mediaposition or tracking detection. The beams of coherent light arereflected from media 31 and return through second substrate 21 and firstsubstrate 11 to be detected by detector 17. Since the elements are allin their designed optical alignment by virtue of the placement of themetalization pads, there is no need to energize the laser and move theelements relative to each other to bring them into optical alignment. Inother words, passive alignment is used rather than the active alignmentrequiring operation of the laser as in the prior art. It will berecognized that although the beams preferably pass first through thediffractive optical element in surface 19, the order of the opticalelements in the light path could be changed or the elements could becombined into one more complex element without departing from the scopeof the invention.

FIG. 4 is another side view of the assembly of FIG. 3. As shown in FIG.4, the light emitted by edge emitting laser 25 comes out substantiallyparallel to the plane of component surface 13 and must be directednormal to the component surface by the 45 degree surface of mirror 33.The light can then pass through substrate 11, a diffractive opticalelement in surface 19, a refractive lens 61 in surface 25, substrate 21and be reflected from media 31 as shown in FIGS. 1 and 3.

FIG. 5 is a plan top view of the component surface 13 looking downthrough transparent substrate 11. Electrical contact metalizations 39,41, 43 and 45 provide electrical connections to detecting photo-diodesin detector 17. Centered under detector 17 is a metalized area 53 havingthree apertures through which light reflected from media 31 is received.Solder ball alignment areas 47 on each side of area 53 serve both aselectrical contacts and as alignment mechanisms in this embodiment. Theareas 49 are also solder ball pads and serve to align and connect thelaser 35 to the first substrate and provide current to laser 15. Areas51 on the other hand only provide mechanical alignment and mechanicalattachment of mirror 33 to first transparent substrate 11.

The hologram surface 19 appears in FIG. 6 in plan view, again lookingdown onto substrate 11. Hologram surface 19 has metalized area 55 whichacts as a mask to reduce stray light but allow three beams created bydiffractive optics from the light from laser 15 to be directed to media31 from which they are reflected to reach detector 17 through the fiveapertures shown in metallized areas 59. Surrounding metalized area 55 isa diffraction grating 57 that scatters stray light from laser 15 so thatit does not adversely affect detector 17.

FIG. 7 shows the refractive lens surface 25, again in plan view lookingdown, this time through substrate 21. Lens 61 in combination with thediffractive optical elements in mask 55 shape and focus the laser lightinto three spots of approximately 20 μm diameter and spaced atapproximately 100 μm onto media 31. Lenses 63 and 65 focus the lightreflected from media 31 through mask 59 to detector 17 for positioncontrol and/or reading. Lens 67 focuses reflected light to thephoto-diode of detector 17 that provides an intensity level signal tothe power control circuits which control the electrical power providedto laser

Surrounding both surface 19 and surface 25 is an attachment area showngenerally as area 71 in FIGS. 6 and 7. Area 71 contains spacing standoff benches and is the area in which an adhesive is placed in order tojoin substrate 21. The standoff benches passively define a proper ordesired vertical spacing or alignment. Preferably the adhesive isultraviolet light cured adhesive that can be laid down without concernfor time to harden. The adhesive is placed in areas 71 and then afterthe substrates 11 and 21 are aligned, the assembly is flooded withultra-violet light to catalyze the adhesive.

In an alternate embodiment, the adhesive is replaced withphotolithographically placed metalization pads and the two substratesare joined using solder ball technology.

FIG. 8 shows three diffractive optical elements 73, 75 with mask 55.These three elements provide the five beams of light to be reflectedfrom the media, the three main rays of which are shown in FIG. 3.Element 75 provides the power control beam that is reflected from themedia and is received at aperture 79 in mask 59 as shown in FIG. 8.Elements 73 and 77 each provide two beams that interfere at the mediasurface to create a dark band with two light bands on either side of thedark bands. The light bands are reflected back down to the pairs ofapertures 81, 83 and 85, 87 shown in FIG. 8 to provide the varying lightintensity that is used to detect an optical track on the media. Theapertures 73, 75 and 77 containing diffractive elements are eachapproximately 100 μm long and 20 μm wide.

Referring now to FIG. 9, the apertures of FIG. 8 are shown enlarged. Theends of each aperture 73, 75 and 77 are provided with an irregularboundary that change the orientation of the interference fringes so thatthey are not parallel with the optical track being detected and accuracyis improved.

FIG. 10 shows the two substrates 11 and 21 prior to their beingassembled into optical assemblies and diced. Because each element hasbeen accurately placed on each substrate using photolithography, theentire wafers can be aligned and joined prior to being diced into chipswithout the need to energize any of the laser devices on the substrate11. FIG. 10 shows the substrates inverted from the way they are shown inFIGS. 2, 3 and 4 in order to show the lasers, mirrors and detectors inplace on top of each die.

Prior to putting the wafers together, the adhesive material 23 is placedin the area 71 of each die on at least one of the wafers. After theadhesive is placed, the two wafers are placed one above the other andaligned. In one embodiment of the invention, a known photolithographicmask aligning tool is used with vernier fiduciary marks 93 and 95 tomonitor the relative displacement of the two substrates until they arein alignment with each other. The substrate 11 can then be lowered ontosubstrate 21, the alignment rechecked, and the adhesive catalyzed byultraviolet light.

In another embodiment, the two wafers are passively aligned using thealignment means 91. Three forms of alignment means are contemplated andshown in FIGS. 11A, 11B and 11C. One, shown in FIG. 11A, takes the formof V-shaped grooves 97 etched into matching faces of the substrates 11and 21. These grooves are then aligned with sphere 99 to index the twowafers into alignment. Note that only a few grooves and spheres areneeded to align all of the dies while they are still together as awafer. Another embodiment of the alignment means, shown in FIG. 11B,comprises photolithographically placed metalization pads 101 which arethen connected by reflowing a solder ball 103. In a still furtherembodiment of FIG. 11C, a bench 105 is raised by etching the surroundingsurface and the bench 105 is indexed into a recess 107, also created byphotolithographically placed etchant, preferably reactive ion etchant.

In the adhesive area 71 of each die, means may be needed to accuratelyspace the two substrates from each other. Spacing is accomplished in oneembodiment by means of a bench 109 shown in FIG. 11D. Three or morebenches 109 are located in the area 71 around each die in an adhesivewith high compressive. In another embodiment, the solder bumps or ballsand metalizations are used in area 23 accomplishing both attachment andalignment as shown in FIG. 11B. Alternately, when an adhesive with highcompressive strength is chosen, only three or more such benches areneeded for spacing the entire wafers and after the adhesive has set, thejoined wafers can be diced without substrate spacing.

Referring now to FIG. 12, a method of photolithographically placing anoptical element on a substrate surface 25 in alignment with diffractiveelements and/or electrical devices is shown. A refractive opticalelement in the form of a microlens 115 is formed by placing a circularlayer of photoresist 111 on a surface of optical material using a mask.The photoresist is then partially flowed using controlled heat so thatthe photoresist assumes a partially spherical shape 113. Thereafter, thesurface is etched and a refractive element 115 having substantially thesame shape as the photoresist 113 is formed by the variable etch rate ofthe continuously varying thickness of the photoresist 113. In the eventthat a hybrid optical element is desired, the microlens 115 is furtherprocessed by etching or embossing steps. In one embodiment, a layer ofphotoresist 117 is placed over the microlens 115 and exposed through aphotolithographic mask with the phase pattern of a diffractive opticalelement. When the exposed photoresist is then developed, the surface ofthe microlens can be further etched with the diffractive optical elementpattern to produce a hybrid optical element 119. In another embodiment,a polymer is placed over the microlens in place of the photoresist andthe phase pattern is embossed into the polymer as shown at 121. It alsowill be understood that although a convex element has been shown, thesame technique can be used to create a concave microlens.

Having described the invention in terms of preferred embodimentsthereof, it will be recognized by those skilled in the art of opticalsystem design that various further changes in the structure and detailof the implementations described can be made without departing from thespirit and scope of the invention. By way of example, the diffractiveoptical elements may be placed on the same surface of a substrate onwhich the electronic components are accurately placed with thesediffractive optical elements using photolithography. Likewise refractiveoptical elements may be placed using photolithography in alignment onthe other surface of the same substrate thereby allowing an entireoptical assembly to be fabricated using but one substrate without theneed for actively energizing a light source in the assembly toaccomplish alignment.

FIG. 13 is a cross sectional view illustrating an integrated opticalhead wherein the laser chip 211, the optical detector chip 213, and theprecision mirror 215 are mounted on a silicon substrate 217. Inaddition, a first transparent substrate 219 including a diffractiveoptical element 221 is mounted on the silicon substrate 217, and asecond transparent substrate 223 including a refractive optical element225 is mounted on the first transparent substrate 219. Moreover, each ofthe substrates 217, 219, and 223 are aligned and secured so that lightgenerated by the laser chip 211 is reflected by the precision mirror 215through the first transparent substrate 219 and the diffractive opticalelement 221, and through the second transparent substrate 223 and therefractive optical element 225 to the media 224. The light is thenreflected back through the second transparent substrate 223 and thefirst transparent substrate 219 to the optical detector chip. Thisstructure can also include separate diffractive elements 226 onsubstrate 219. Similar diffractive elements 326 and 425 are respectivelyshown in FIGS. 14 and 15.

More particularly, the diffractive optical element 221 splits the lightfrom the laser into three separate beams, and the refractive opticalelement 225 focuses each of these three beams onto respective portionsof the media 224. The three beams are each reflected back through thefirst and second transparent substrates 223 and 219 to three respectiveportions of the optical detector chip 213. The transparent substrates219 and 223 can be attached and aligned using attachment areas 227 asdiscussed above, for example, with reference to FIGS. 3, 4, 10, 11, and12. Similarly, the silicon substrate 217 can be attached to thetransparent substrate 219 using the attachment areas 229. Accordingly,the laser 211, mirror 215, and optical detector 213 on the siliconsubstrate 217 can be passively aligned with the diffractive opticalelement 221 on the transparent substrate 219 and with the refractiveoptical element 225 on the transparent substrate 223.

The attachment areas 229 can be provided by etching a recess into thesilicon substrate 217 in which the laser, mirror, and detector areprovided. In other words, the unetched portions of the substrate act asspacers. In addition, the substrates 217 and 219 can be bonded usingsolder material 220. Furthermore, the mirror 215 can be provided by anangled sidewall of the substrate adjacent the recess therein.Alternately, the attachment areas 229 can include spacers to providespace between the substrates 217 and 219 wherein the spacers areseparate from the substrate 217. The mirror 215 can be a separateelement attached to the substrate 217, or the mirror 215 can serve as aspacer.

In FIG. 14, the refractive optical element 325 and the diffractiveoptical element 321 are provided on opposite sides of a singletransparent substrate 319. As before, the laser chip 311, the mirror315, and the optical detector chip 313 are provided on a siliconsubstrate 317 which is attached to the transparent substrate 319 usingattachment areas 329 and solder material 330 as discussed above.Accordingly, the two substrates can be passively aligned so that lightgenerated by the laser chip 311 is reflected by the mirror 315 throughthe refractive optical element 325 and the diffractive optical element321 to the surface of the media 324. The light is reflected from themedia 324 through the transparent substrate 319 to the optical detectorchip 313. The refractive optical element 325 focuses the reflectedlight, and the diffractive optical element 321 separates the focusedlight into three beams which are directed to the media 325 and reflectedto three separate detecting regions of the optical detector chip 313.The silicon substrate and the transparent substrate can be aligned andattached as discussed above with regard to FIG. 13.

The optical head of FIG. 15 is similar to that of FIG. 14 with theexception that the optical elements have been modified. In FIG. 15, thediffractive optical element 421 separates the reflected light into threebeams which are transmitted to the media 424 and reflected back towardthe transparent substrate 419. A separate diffractive element 425 isthen provided on the transparent substrate 419 for each of the reflectedbeams. Accordingly, each of the diffractive optical elements 425 focusesa respective reflected beam onto a respective detector portion of theoptical detector chip 413. As before, the laser chip 411, mirror 415,and optical detector chip 413 are provided on a silicon substrate 417which is aligned with and attached to the transparent substrate 419through the attachment areas 429 and solder material 420.

In the structures of FIGS. 13, 14, and 15, the substrates can bepassively aligned and attached using patterns formedphotolithographically. For example, each of the adjacent substrates canbe passively aligned using V-shaped grooves as discussed above withregard to FIG. 11A, photolithographically placed metallization pads asdiscussed above with reference to FIG. 11B, or a raised bench indexedinto a recess as discussed above with regard to FIG. 11C. Furthermore,accurate spacing can be provided using a bench as discussed above withregard to FIG. 11D.

The structures of FIGS. 13, 14, and 15 can be fabricated by firstforming a support wafer, such as a silicon wafer, having a plurality oflasers, mirrors, and detectors thereon, and passively aligning andattaching the support wafer to a transparent wafer having a plurality ofoptical elements formed thereon. A plurality of optical heads can thusbe formed simultaneously and then diced apart by cutting both thetransparent and support substrates simultaneously. Alternately, thesilicon wafer can be diced and individual laser/detector assembliesaligned and attached to the transparent substrate such as by flip-chipattachment. By first forming a support wafer with lasers thereon, thelasers can be tested and burned-in independently.

As discussed above, the recesses can be etched into the supportsubstrate, and the lasers can be provided in respective recesses. Moreparticularly, the recesses can be formed by isotropically etching asilicon substrate along a crystalline plane so that a sidewall of therecess has a 45 degree angle. The sidewall of the recess can thus beused as the mirror. Moreover, the unetched portions of the silicon canbe used to provide spacers when bonding the silicon with the transparentwafer or substrate. In addition, while the detector is illustrated as achip on the silicon substrate, the detector can be formed in the surfaceof the substrate. For example, a photosensitive diode can be formed inthe silicon substrate to provide photodetection.

In the drawings and specification, there have been disclosed illustratedpreferred embodiments of the invention, and although specific terms areemployed, the terms are used in a descriptive sense only and not forpurposes of limitation. The invention has been described in considerabledetail with specific reference to these illustrated embodiments. It willbe apparent, however, that various modifications and changes can be madewithin the spirit and scope of the invention as described in theforegoing specification and as defined in the appended claims.

That which is claimed is:
 1. An apparatus for use with data storagemedia and comprising:an integrated optical head comprisinga firsttransparent substrate being optically transparent and having opposingfirst and second faces, a support substrate adjacent said first face ofsaid first substrate, wherein said support substrate includes a lightsource and an optical detector, wherein said light source emits lightthrough said first substrate and toward the data storage media, andwherein said optical detector detects light reflected from the datastorage media and through said first substrate, at least one firstoptical element on said first transparent substrate and positioned in anoptical path between said light source and said optical detector, andfirst passive alignment means for passively aligning said firsttransparent substrate and at least one of either said light source orsaid optical detector; and head positioning means for positioning saidintegrated optical head relative to the data storage media.
 2. Anapparatus according to claim 1 wherein said first passive alignmentmeans comprises:a first plurality of contact pads on the first face ofsaid first transparent substrate; a second plurality of contact pads onsaid support substrate; and solder material between said first andsecond plurality of contact pads to passively align said firsttransparent substrate and at least one of either said light source orsaid optical detector.
 3. An apparatus according to claim 1 wherein saidpassive alignment means provides a predetermined spacing between saidfirst substrate and at least one of either said light source or saidoptical detector.
 4. An apparatus according to claim 1 wherein saidfirst passive alignment means comprises mechanical mating means betweenthe first face of said first transparent substrate and said supportsubstrate.
 5. An apparatus according to claim 4 wherein said mechanicalmating means comprises a plurality of features defined between the firstface of said first transparent substrate and said support substrate. 6.An apparatus according to claim 1 wherein said at least one firstoptical element comprises at least one of a diffractive optical elementand a refractive optical element; and wherein said at least one firstoptical element is on at least one of the first face and the second faceof said first substrate.
 7. An apparatus according to claim 1 whereinsaid at least one first optical element comprises a hybrid opticalelement including diffractive and refractive portions.
 8. An apparatusaccording to claim 1 further comprising:a second transparent substratepositioned adjacent said second face of said first transparentsubstrate, said second transparent substrate being optically transparentand having opposing first and second faces; and at least one secondoptical element on said second transparent substrate in the optical pathbetween said light source and said optical detector.
 9. An apparatusaccording to claim 8 wherein said at least one second optical elementcomprises a hybrid optical element including diffractive and refractiveportions.
 10. An apparatus according to claim 8 further comprisingsecond passive alignment means for passively aligning said firsttransparent substrate and said second transparent substrate so that saidat least one second optical element is aligned in the optical pathbetween said light source and said optical detector.
 11. An apparatusaccording to claim 10 wherein said second passive alignment meanscomprises:a third plurality of contact pads on the second face of saidfirst transparent substrate; a fourth plurality of contact pads on thefirst face of said second transparent substrate; and solder materialbetween said third and fourth plurality of contact pads to passivelyalign said first transparent substrate and said second transparentsubstrate.
 12. An apparatus according to claim 10 wherein said secondpassive alignment means comprises mechanical mating means between saidsecond face of said first transparent substrate and said first face ofsaid second transparent substrate.
 13. An apparatus according to claim12 wherein said mechanical mating means comprises a plurality ofmechanically mating features.
 14. An apparatus according to claim 1wherein said light source comprises an edge emitting light source andfurther comprising:a mirror adjacent said support substrate and in theoptical path between said light source and said optical detector.
 15. Anoptical system comprising:a first transparent substrate having alignmentareas photolithographically placed on a first face and at least onediffractive optical element photolithographically formed in a secondface, the photolithography of the first face being aligned with thephotolithography of the second face; a support substrate having at leastone electronic device thereon, wherein said support substrate is mountedto said first face of said first transparent substrate by said alignmentareas causing passive optical alignment between said electronic deviceand said diffractive optical element; substrate alignment areas on thesecond face of said first transparent substrate; and a secondtransparent substrate having mating substrate attachment areas on afirst face for attaching said first transparent substrate in alignmentwith said second transparent substrate.
 16. An optical system accordingto claim 15 wherein said substrate attachment areas further comprisesphotolithographically placed metalization pads and solder material. 17.An optical system according to claim 15 wherein said first transparentsubstrate is part of a first wafer and said second transparent substrateis part of a second wafer, said first transparent substrate and saidsecond transparent substrate having been aligned by alignment offiducial marks on said first wafer with fiducial marks on said secondwafer respectively, said wafers having been attached to each other bysaid attachment areas prior to being diced into separate assemblies. 18.An optical system according to claim 15 further comprising refractiveoptical elements on a face of said second transparent substrate.
 19. Anoptical system according to claim 15 wherein said system is a mediareader and said at least one electronic device further comprises:a lightsource light source; and a plurality of light detectors.
 20. An opticalsystem according to claim 19 wherein said at least one diffractiveoptical element which divides the light from said light source into aplurality of beams for reflection from said media, each reflected beamhaving an individual optical element on the first surface of said secondtransparent substrate for transmitting said reflected beam to adetector.
 21. An optical system according claim 15 further comprising:alight source mounted to the first face of said support substrate,wherein said diffractive optical element divides light from said lightsource into a plurality of beams for refection from a media; a detectordevice having a plurality of light sensitive areas, said detector beingmounted to said support substrate by said alignment areas; and aplurality of optical elements on the first surface of said secondtransparent substrate, each reflected beam passing through an individualoptical element on the first surface of said second transparentsubstrate for transmitting said reflected beam to one of said lightsensitive areas of said detector.
 22. An optical system according claim15 wherein said passive optical alignment provides a predeterminedspacing between said electronic device and said diffractive opticalelement.
 23. An integrated optical system comprising:a first transparentsubstrate having alignment areas photolithographically placed on a firstface and at least one hybrid optical element photolithographicallyformed in a second face, the photolithography of the first face beingaligned with the photolithography of the second face; and a supportsubstrate having at least one electronic device thereon, wherein saidsupport substrate is mounted to said first face of said firsttransparent substrate by said alignment areas causing passive opticalalignment between said electronic device and said hybrid opticalelement.
 24. An integrated optical system of claim 23 wherein the hybridoptical element formed in the second face of the first transparentsubstrate further comprises:a metal layer defining an aperture; and adiffractive optical element located within the aperture for directinglight from a light source in the electronic device to a media.
 25. Anintegrated optical head for use with data storage media, said integratedoptical head comprising:a first transparent substrate being opticallytransparent and having opposing first and second faces; a supportsubstrate adjacent said first face of said first transparent substrate,wherein said support substrate includes a light source and an opticaldetector, wherein said light source emits light through said firsttransparent substrate and toward the data storage media, and whereinsaid optical detector detects light reflected from the data storagemedia and through said first transparent substrate; at least one firstoptical element on said first transparent substrate and positioned in anoptical path from said light source to said optical detector; andmechanical mating means between said first face of said firsttransparent substrate and said support substrate for passively aligningsaid first transparent substrate and at least one of either said lightsource or said optical detector.
 26. An integrated optical headaccording to claim 25 wherein said mechanical mating means comprises aplurality of mechanically mating features defined between the firstsurface of said first transparent substrate and said support substrate.27. An integrated optical head according to claim 25 wherein said atleast one first optical element comprises at least one of a diffractiveoptical element and a refractive optical element.
 28. An integratedoptical head according to claim 25 wherein said at least one firstoptical element comprises a hybrid optical element including diffractiveand refractive portions.
 29. An integrated optical head according toclaim 25 further comprising:a second transparent substrate positionedadjacent the second face of said first transparent substrate, saidsecond transparent substrate being optically transparent and havingopposing first and second faces; and at least one second optical elementon said second transparent substrate.
 30. An integrated optical headaccording to claim 29 further comprising:passive alignment means forpassively aligning said first transparent substrate and said secondtransparent substrate so that said at least one second optical elementis aligned in the optical path between said light source and saidoptical detector.
 31. An integrated optical head according to claim 29wherein said at least one second optical element comprises at least oneof a diffractive optical element and a refractive optical element. 32.An integrated optical head according to claim 25 wherein said mechanicalmating means provides a predetermined spacing between said substrate andat least one of either said light source or said optical detector. 33.An integrated optical head for use with data storage media, saidintegrated optical head comprising:a first transparent substrate beingoptically transparent and having opposing first and second faces; afirst plurality of contact pads on the first face of said firsttransparent substrate; a support substrate adjacent said first face ofsaid first transparent substrate, wherein said support substrateincludes a light source and an optical detector, wherein said lightsource emits light through said first transparent substrate and towardthe data storage media, and wherein said optical detector detects lightreflected from the data storage media and through said first transparentsubstrate; a second plurality of contact pads on said support substrate;at least one first optical element on said first transparent substrateand positioned in an optical path between said light source and saidoptical detector; and solder material between said first and secondplurality of contact pads for passively aligning said first transparentsubstrate and at least one of either said light source or said opticaldetector.
 34. An integrated optical head according to claim 33 whereinsaid at least one first optical element comprises at least one of adiffractive optical element and a refractive optical element; andwherein said at least one first optical element is on at least one ofthe first face and the second face of said first substrate.
 35. Anintegrated optical head according to claim 33 wherein said at least onefirst optical element comprises a hybrid optical element includingdiffractive and refractive portions.
 36. An integrated optical headaccording to claim 33 further comprising:a second transparent substratepositioned adjacent said first substrate said second transparentsubstrate being optically transparent and having opposing first andsecond faces; and at least one second optical element on said secondtransparent substrate.
 37. An integrated optical head according to claim33 wherein said plurality of solder bumps provide a predeterminedspacing between said first substrate and at least one of either saidlight source or said optical detector.
 38. An article during themanufacture of a plurality of integrated optical heads, said articlecomprising:a first transparent wafer being optically transparent andhaving opposing first and second faces; a second transparent wafer beingoptically transparent adjacent the second face of said first transparentwafer and having opposing first and second faces, and a plurality ofoptical elements on said second transparent wafer; a support waferadjacent the first face of said first transparent wafer wherein saidsupport wafer has a plurality of light sources and optical detectorsthereon; and passive alignment means for passively aligning said firsttransparent wafer and said second transparent wafer so that saidplurality of light sources and optical detectors are aligned with saidplurality of optical elements.
 39. An article according to claim 38further comprising an adhesive for securing said first and second waferstogether.
 40. An article according to claim 38 wherein said plurality ofoptical elements comprises diffractive optical elements.
 41. An articleaccording to claim 38 wherein said plurality of optical elementscomprises refractive optical elements.
 42. An article according to claim38 wherein said plurality of optical elements comprises hybrid opticalelements, each including diffractive and refractive portions.
 43. Anarticle according to claim 38 wherein said passive alignment meansprovides a predetermined spacing between said first wafer and saidsecond wafer.
 44. An article according to claim 38 wherein said passivealignment means comprises:a first plurality of contact pads on thesecond face of said first wafer; a second plurality of contact pads onthe first face of said second wafer; and solder material between saidfirst and second plurality of contact pads to passively align said firstwafer and second wafers.
 45. An article according to claim 38 whereinsaid passive alignment means comprises alignment indicia on said firstwafer and said second wafer.
 46. An article according to claim 38wherein said passive alignment means comprises mechanical mating meansbetween said second face of said first wafer and said first face of saidsecond wafer.
 47. An article according to claim 46 wherein saidmechanical mating means comprises a plurality of mechanically matingfeatures defined in the second surface of said first wafer and the firstface of said second wafer.
 48. A method for making an integrated opticalhead for use with data storage media, the method comprising the stepsof:providing a first transparent substrate having opposing first andsecond faces; forming at least one first optical element on the firsttransparent substrate; providing a support substrate having a lightsource and an optical detector thereon; positioning said supportsubstrate adjacent the first face of the first transparent substrate sothat the light source emits light through said first transparentsubstrate and toward the data storage media and so that the opticaldetector detects light reflected from the data storage media and throughsaid first transparent substrate; and passively aligning the firsttransparent substrate and the support substrate.
 49. A method accordingto claim 48 wherein the step of passively aligning comprises the stepsof:forming a first plurality of contact pads on the first face of saidfirst transparent substrate; forming a second plurality of contact padson said support substrate; and forming solder material between saidfirst and second plurality of contact pads to passively align said firsttransparent substrate and at least one of said light source and saidoptical detector.
 50. A method according to claim 49 wherein the stepsof forming the first and second pluralities of contact pads comprisesforming same using photolithography.
 51. A method according to claim 48wherein the step of passively aligning comprises the steps of:formingmechanically mating features between the first surface of said firsttransparent substrate and said support substrate; and relativelypositioning said first transparent substrate and said support substrateso that said mechanically mating features touch one another.
 52. Amethod according to claim 48 further comprising the steps of:providing asecond transparent substrate comprising at least one second opticalelement; and passively aligning the second transparent substrate withthe second surface of said first transparent substrate so that the atleast one second optical element is positioned in an optical pathbetween said light source and said optical detector.
 53. A methodaccording to claim 52 wherein the steps of providing the first andsecond transparent substrates comprises providing first and secondtransparent wafers; and wherein the step of passively aligning the firstand second transparent substrates comprises passively aligning the firstand second transparent wafers.
 54. A method according to claim 53further comprising the steps of securing the aligned first and secondtransparent wafers together; and dicing the wafers into a plurality ofintegrated optical devices.
 55. A method according to claim 48 whereinsaid step of passively aligning comprises providing a predeterminedspacing between the first substrate and at least one of either saidlight source or said optical detector.
 56. An integrated optical systemcomprising:a first transparent substrate having at least one alignmentarea on a second face; a second transparent substrate mounted to thesecond face, the mounting including a mating alignment area on thesecond transparent substrate for mating with the alignment area andcausing passive optical alignment between the first transparentsubstrate and the second transparent substrate; a support substratehaving a light source and a light detector thereon adjacent a first faceof said first transparent substrate; a holographic optical elementformed on one of said transparent substrates for directing light fromthe light source to a remote target; and a refractive lens formed on theother of said transparent substrates for directing light from the lightsource to the remote target.
 57. An integrated optical system accordingto claim 56 wherein said first and second substrates comprise fusedsilica.
 58. An integrated optical system according to claim 56wherein:the alignment area further comprises a metalized area ofpredetermined size and position; the mating alignment area furthercomprises a metalized area of predetermined size and position; and themounting further comprising solder material of predetermined volume andliquified surface tension for passively pulling the first transparentsubstrate and the second transparent substrate into horizontal alignmentand maintaining the second substrate a predetermined distance from thefirst transparent substrate.
 59. An integrated optical system accordingto claim 56 wherein:the alignment area further comprises an alignmentbench of predetermined height and position; and the mounting furthercomprising adhesive, the bench and the recess interacting to maintainthe first transparent substrate and the second transparent substrate inhorizontal alignment and to maintaining the second substrate apredetermined distance from the first transparent substrate.
 60. Anintegrated optical system according to claim 56 wherein the light sourcefurther comprises a semiconductor light source adjacent to an angledmirror adjacent said support, the light source and the mirror mountedaligned with each other and aligned with the holographic optical elementby flip chip solder bonds.
 61. An integrated optical system according toclaim 56 wherein the holographic optical element formed in the secondface of the first transparent substrate further comprises:a metal layerdefining an aperture; and a diffractive optical element located withinthe aperture for directing light from the light source to the remotetarget.